HomeInternational Rice Research Notesvol. 28 no. 1 (2003)

Chlorophyll Meter-Based N Management for Rice Grown in Soils Amended with Organic Manure

Bijay Singh | Yadvinder Singh | G. S. Sodhi | R. K. Gupta | C. S. Khind | J. K. Ladha | V. Balasubramanian

Discipline: Agriculture



To ensure high yields, rice farmers tend to apply N in excess of the requirements. This often leads to low N-use efficiency as it does not account for large field-to-field variability of soil N supply.  Synchronization of N supply with crop demand is crucial to achieving high yield and N-use efficiency. The chlorophyll meter, also known as the SPAD (soil plant analysis development) meter, can quickly and reliably assess the leaf area-based N status of a crop and can guide need based N fertilizer applications in rice. Although the SPAD meter can be advantageously used to explore N management strategies, cheaper alternate gadgets such as the leaf color chart are already available for use by farmers. An approach based on the application of N when the sufficiency index (defined as SPAD value of the plot in question divided by that of an overfertilized reference plot or strip) falls below 0.90 (Hussain et al 2000) was used to determine the fertilizer N requirement of rice grown in soils amended with farmyard manure (FYM) and green manure (GM).